CXCR2 and neoplasm: The blockade of immune checkpoints of the neutrophil programmed cell death 1 (PD1)/PD-L1 pathway, targeted binding of CXCR2, CXCR4, G-CSF, TGF-β, etc., which in turn inhibits the recruitment, expansion and polarization of tumor neutrophils, may provide some ideas for neutrophil-targeted tumor therapies.